The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A landfill gas (“LFG”) system may consist of many LFG wells connected to a central gas extraction vacuum blower by means of a piping header system. The LFG wells are often used at landfills to extract methane gas that develops below the surface of the landfill from decomposing waste. The vacuum assists in maintaining a desired flow rate of the methane gas out through the wellhead.
The header system has branches and end points that connect the vacuum blower to all of the LFG wells located across a landfill. Currently each LFG wellhead has a single manually adjustable valve that controls gas flow (i.e., the amount of vacuum applied to the well). Each well has the ability to produce some volume of LFG per unit time. The production of LFG will typically vary at least slightly from well to well, and this well-to-well variance may change over time as well.
In actual LFG systems the central vacuum source is never able to apply full vacuum to all wellheads equally. This is typically due to blower sizing and head loss in the piping system. Variations in wellhead valve settings will often affect vacuum availability to other wellheads “downstream” from a given wellhead. In other words, a significant change in a valve setting on wellhead A is expected to change the pipe header conditions for wells in the vicinity of wellhead A. Additionally, changes in overall site conditions (macro changes), most notably barometric pressure, can change overall vacuum blower flow rate and rates of apparent gas production from large numbers of wellheads. Wellhead conditions can also change over time, impacting the production of LFG (e.g., water build-up can restrict LFG flow into the well, etc.). The macro changes lead to the necessity of ongoing optimization and adjustment of the manual LFG valves to achieve various control goals (maximize LFG recovery, control LFG emissions, keep oxygen intrusion low, etc.). Such on-going optimization efforts often necessitate frequent trips to each wellhead at a given landfill by a technician in order to check the LFG flow from each wellhead and make the needed adjustments in an attempt to optimize the LFG flow. As will be appreciated, this manpower requirement can sometimes be costly and time consuming, especially at landfills where dozens or more wellheads are in use.
But perhaps the most significant drawback to present day LFG systems is the inability to factor in the change that an adjustment to the flow valve of one LFG wellhead will make on the LFG flows produced by other LFG wellheads in the vicinity. This variable is typically not considered by technicians when making a flow valve adjustment to each wellhead. Moreover, intelligent information on the real time flow rates from other wellheads is often not readily available to the technician. So situations may exist where a minor adjustment is made by the technician to one specific wellhead (e.g., wellhead “A”) in order to optimize the LFG flow from that well, but this adjustment actually causes a degradation in the flow from one or more other wellheads B and C in the vicinity (e.g., within a 500 ft radius). And then when the technician goes to wellhead B and makes an adjustment to its flow valve, such a change further ends up affecting the LFG flow from wellheads A and C. Thus, it becomes exceedingly difficult, if not impossible, to determine flow valve settings for each of wellheads which optimizes the overall LFG production from all the wells collectively.